The invention relates to an antenna system, comprising at least tow dipole antennas constituting an antenna module and placed above and parallel to a common, artificial ground plane in the form of an electrically conducting plate, feed lines designed as waveguides with air dielectric from the dipoles to a common feeding point and where the dipoles are carried by legs which can form part of the feed lines, and a method of manufacturing an antenna module for an antenna system, where the antenna system is made up of active antennas with matching feed lines and a common ground plane.
For instance, such antennas are used as base station antennas, i.e. the antenna system is placed in a mast and is coupled to a transmitter-receiver System via a coaxial cable. The frequency range is normally in the range of 450-900 MHz, but the antenna system can also be used in other frequency ranges.
Known antenna systems of this type are built up of individual parts by welding, soldering or screwing together the antenna parts, the feed line parts, etc. In this manner an antenna with the required electrical qualities is obtained. However, the production costs are comparatively high, as all individual parts must have precise dimensions after the assembly operations due to the comparatively high frequency range for which the antenna system is to be used. Moreover, the numerous assemblies are time-consuming and require qualified and well-educated staff in the production. Besides, an antenna construction of this type does not have optimum electrical qualities, because the many assemblies cause discontinuity in the materials used resulting in varying electrical qualities at high frequencies. Consequently, assemblies made by soldering or screwing may result in various unwanted signal components in the antenna signal.